Biology subjects

Xie, X.

Publications and source records attributed to Xie, X..

At least 91 records · Page 5Linked to original sources

bioRxiv2024

Mechanistic Insights into Dengue Virus Inhibition by a Clinical Trial Compound NITD-688

Dengue, caused by the dengue virus (DENV), presents a significant public health challenge with limited effective treatments. NITD-688 is a potent pan-serotype DENV inhibitor currently in Phase II clinical trials. However, its mechanism of action is not fully understood. Here, we present the molecular details of how NITD-688 inhibits DENV. NITD-688 binds directly to the nonstructural protein 4B (NS4B) with nanomolar affinities across all four DENV serotypes and specifically disrupts the interaction between NS4B and nonstructural protein 3 (NS3) without significantly changing the interactions between NS4B and other viral or host proteins. NS4B mutations that confer resistance to NITD-688 reduce both NITD-688 binding to NS4B and disruption of the NS4B/NS3 interaction. Specifically, NITD-688 blocks the interaction of NS3 with a cytosolic loop within NS4B. This inhibits the formation of new NS4B/NS3 complexes and disrupts pre-existing complexes in vitro and DENV-infected cells, ultimately inhibiting viral replication. Consistent with this mechanism, NITD-688 retains greater potency in cellular assays with delayed treatment compared to JNJ-1802, another NS4B inhibitor that has been studied in Phase II clinical trials. Together, these findings provide critical insights into the mechanism of action of NITD-688, facilitating the development of novel flavivirus NS4B inhibitors and informing future clinical interventions against DENV.

microbiology↗

bioRxiv2024

A new class of natural anthelmintics targeting lipid metabolism

Parasitic helminths are a major global health threat, infecting nearly one-fifth of the human population and causing significant losses in livestock and crops. Resistance to the few anthelmintic drugs is increasing. Here, we report a set of avocado fatty alcohols/acetates (AFAs) that exhibit nematocidal activity against four veterinary parasitic nematode species: Brugia pahangi, Teladorsagia circumcincta and Heligmosomoides polygyrus, as well as a multidrug resistant strain (UGA) of Haemonchus contortus. AFA shows significant efficacy in H. polygyrus infected mice. In C. elegans, AFA exposure affects all developmental stages, causing paralysis, impaired mitochondrial respiration, increased reactive oxygen species production and mitochondrial damage. In embryos, AFAs penetrate the eggshell and induce rapid developmental arrest. Genetic and biochemical tests reveal that AFAs inhibit POD-2, encoding an acetyl CoA carboxylase, the rate-limiting enzyme in lipid biosynthesis. These results uncover a new anthelmintic class affecting lipid metabolism.

cell biology↗

bioRxiv2024

PAG orchestrates T cell immune synapse function by binding to actin

Many immunotherapies impact T cell function by impacting the immune synapse. While immunotherapy is extremely successful in some patients, in many others, it fails to help or causes complications, including immune-related adverse events. Phosphoprotein Associated with Glycosphingolipid Rich Microdomains 1 (PAG) is a transmembrane scaffold protein with importance in T cell signaling. PAG has 10 tyrosine phosphorylation sites where many kinases and phosphatases bind. PAG is palmitoylated, so it localizes in lipid rafts of the membrane, and contains a C-terminal PDZ domain to link to the actin cytoskeleton. As a link between signaling-protein-rich membrane regions and the actin cytoskeleton, PAG is an exciting and novel target for manipulating immune function. Here, we sought to determine if PAG works with actin to control T cell synapse organization and function. We found that PAG and actin dynamics are tightly coordinated during synapse maturation. A PDZ domain mutation disrupts the PAG-actin interaction, significantly impairing synapse formation, stability, and function. To assess the impact of the PDZ mutation functionally in vivo, we employed a mouse model of type IV hypersensitivity and an OVA-tumor mouse model. In both systems, mice with T cells expressing PDZ-mutant PAG had diminished immune responses, including impaired cytotoxic function. These findings highlight the importance of the PAG-actin link for effective T cell immune synapse formation and function. The results of our study suggest that targeting PAG is a promising approach for modulating immune responses and treating immune-related diseases. One Sentence SummaryAdaptor protein PAG links to the actin cytoskeleton, and this link is essential for T cell synapse formation and cytotoxic function.

immunology↗

bioRxiv2024

Modeling Mountain Pine Beetle Abundance in Novel Hosts

The mountain pine beetle has recently expanded its range into northern and central Alberta, posing an immediate threat to the novel host, jack pine. To date, some experiments suggest that jack pine has limited defensive capabilities despite of the restrictions from the physical environment. In this work, we explore the susceptibility of jack pine compared to the primary host, lodgepole pine, evaluating the risk of potential range expansion into Canadas boreal forest. We employ a hierarchical model, incorporating environmental and ecological covariates, to examine mountain pine beetle dynamics in a pine forest with lodgepole, hybrid and jack pines. Our results show that pine species significantly influence the probability of being killed, with jack pine being less likely to be infested than lodgepole pine, all else being equal. The hierarchical model demonstrates that beetles perform poorer in jack pine, characterized by a reproduction rate 0.16 times that of non-jack pine. Although jack pine is a suitable host, our results indicate that the number of infestations in jack pine could be lower than in lodgepole pine, with a reduced probability of emerging beetles.

ecology↗

bioRxiv2024

Restoration of PKM1 improves functional maturation of human stem-cell derived-β cell by regulating PEP metabolism

Human stem cell-derived {beta} (SC-{beta}) cells still exhibit limited glucose response required for insulin secretion due to glycolytic bottlenecks, yet how these metabolic abnormalities impact glucose response and functional maturation of SC-{beta} cells remains unclear. In this study, we identified a metabolic checkpoint located at PEP accumulation that impeded the functional maturation, which was rescued by restoration of pyruvate kinase 1 (PKM1). Glucose-tracing metabolomics in human stem cell-derived islets revealed abnormal glycolytic PEP accumulation at resting condition, resulting in impaired calcium response and insulin secretion upon high glucose or glycolytic metabolite stimulation. Mechanistically, elevated PEP significantly raised intracellular basal calcium levels, leading to downregulated expression of genes involved in TCA cycle elucidated by single cell transcriptomics. Furthermore, the activity of pyruvate kinase, which metabolizes PEP, was notably reduced due to low PKM1 expression. By overexpressing PKM1, the impairment of TCA-related genes caused by PEP accumulation was reversed via modulating PEP metabolism, resulting in enhanced calcium responses and insulin secretion upon high glucose stimulation. Together, we discovered a novel role of PKM1-regulated PEP metabolism in mediating the functional maturation of human SC-{beta} cells. This study highlights the importance of metabolic reprogramming in human SC-{beta} cell maturation, advancing cell therapy approaches for diabetes treatment.

cell biology↗

bioRxiv2024

Absorbing molecules make both abdomen and back transparent in live mice

The field of tissue clearing has experienced rapid advancements in the past decades. Tissue clearing techniques primarily rely on physical or chemical approaches to match the refractive indices of cells and their surrounding medium, thereby reducing light scattering and rendering the tissue optically transparent. By doing so, it becomes possible to utilize fluorescence imaging and 3D reconstruction techniques to observe and analyze the contents and structures of tissues at a cellular level. However, effective research on in vivo tissue clearing remains limited due to the involvement of toxic substances and the removal of water or lipids. A recent article in Science reports a technique that achieves tissue transparency in live animals with absorbing molecules, marking a significant advancement in the field of in vivo tissue clearing. Although this work has great potential for imaging and light-based therapeutics, some labs found it difficult to reproduce the reported results. In this study, we report the successful reproduction of the findings, provide experimental details that we identified as key to reproducibility, present a new transparency effect observed in the back of live mice, which was not shown in the original paper, and offer insights into the future development and applications of in vivo clearing reagents.

bioengineering↗

bioRxiv2024

Efficient Inference, Training, and Fine-tuning of Protein Language Models

Protein language models have shown great promise in predicting protein structure, function, and the effects of missense variants on protein fitness. However, their use has been limited by the substantial computational resources required. In this work, we focus on improving the computational efficiency of protein language models (PLMs), specifically the Evolutionary Scale Modeling (ESM) family, to increase the accessibility of PLMs. By implementing optimizations such as FlashAttention and Partition-Attention, a novel technique designed to handle proteins of variable length, we achieved a 16-fold speedup in inference time and reduced memory usage by 3 to 14 times for long proteins. Additionally, 4-bit quantization applied to billion-parameter models led to a 2 to 3 times reduction in memory consumption with minimal performance loss in the missense variant effect prediction task. Training efficiency was also improved, with a 6-fold reduction in runtime achieved through activation checkpointing and the DeepSpeed Zero-Offload strategy. For fine-tuning, we employed parameter-efficient methods, enabling state-of-the-art predictions of protein properties and functions by training only the model head or a small fraction of adapter weights. For instance, we achieved a Spearmans correlation coefficient of 70% in melting point prediction and an 87% area under the precision-recall curve (AU-PRC) for transcription factor prediction. Our efficient ESM (ESME) implementation significantly lowers the barrier to using these powerful models, making them accessible to academic laboratories with limited computational resources. The ESME implementation is available on PyPI (pypi.org/project/esm-efficient) and GitHub (github.com/uci-cbcl/esm-efficient).

bioinformatics↗

bioRxiv2024

Barley is a potential trap crop for root parasitic weeds broomrapes

Root parasitic weeds broomrapes (Phelipanche and Orobanche spp.) cause devastating damages to agricultural production all over the world. The seeds of broomrapes germinate when they are exposed to germination stimulants, mainly strigolactones (SLs), released from roots of any plant species, while broomrapes parasitize only dicot plants. Therefore, monocots can be trap crops for broomrapes, as they induce seed germination but are not parasitized. In this study, we examined two European and one Japanese cultivars of barley for their potentials as trap crops for broomrapes and found that the European cultivars, Sebastian and Golden promise, are good potential trap crops as they produce more SLs and exhibit higher mycorrhizal colonization rates as compared to the Japanese cultivar Shunrai.

plant biology↗

bioRxiv2024

The dinucleotide structure of NAD enables specific reduction on mineral surfaces

Nucleotide-derived cofactors could function as a missing link between the informational and the metabolic part at lifes emergence. One well-known example is nicotinamide dinucleotide (NAD), one of the evolutionarily most conserved redox cofactors found in metabolism. Here, we propose that the role of these cofactors could even extend to missing links between geo- and biochemistry. We show NAD+ can be reduced under close-to nature conditions with nickel-iron-alloys found in water-rock-interaction settings rich in hydrogen (serpentinizing systems) and that nicotinamide mononucleotide (NMN), a precursor molecule to NAD, has different properties regarding reduction specificity and sensitivity than NAD. The additional adenosine monophosphate (AMP) "tail" of the dinucleotide, a shared trait between many organic cofactors, seems to play a crucial mechanistic role in preventing overreduction of the nicotinamide-bearing nucleotide. This specificity is also connected to the used transition metals. While the combination of nickel and iron promotes the reduction of NAD+ to 1,4-NADH most efficiently, in the case of NMN, the presence of nickel leads to the accumulation of overreduction products. Testing the reducing abilities of both NADH and NMNH under abiotic conditions showed that both molecules act as equally effective, soluble hydride donors in non-enzymatic, proto-metabolic stages of lifes emergence.

evolutionary biology↗

bioRxiv2024

SIRT4 enhances the cytotoxicity of NK cells toward hepatic stellate cells and reverses liver fibrosis via AMPKα/P-p53/NKG2DL pathway

Natural killer (NK) cells exhibit antifibrotic properties in liver fibrosis (LF) by suppressing activated hepatic stellate cells (HSCs). SIRT4, a mitochondrial regulatory protein, plays a crucial role as a link between energy metabolism and cell viability. However, the role of SIRT4 in the cytotoxicity of NK cells toward HSCs remains unexplored. In this study, we found that SIRT4 was markedly downregulated in both mouse models and patients with LF. The loss of SIRT4 reduced the cytotoxicity of NK cells against activated HSCs, while its overexpression enhanced this cytotoxicity. Mechanistically, SIRT4 activates AMPK to promote p53 phosphorylation and facilitates its nuclear translocation, which induces the transcription of ULBP1 and ULBP2, members of the NK group 2D Legend (NKG2DL) family of molecules. Finally, overexpression of SIRT4 activated mouse hepatic NK cells and reversed LF by constructing adeno-associated viruses (AAV) that specifically target HSCs. Thus, SIRT4 is essential for the cytotoxicity of NK cells toward HSCs, and AAV8-pGAFP-SIRT4 may serve as a therapeutic approach for managing LF. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/615768v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@1e6e987org.highwire.dtl.DTLVardef@edcc2dorg.highwire.dtl.DTLVardef@1f7c2bcorg.highwire.dtl.DTLVardef@111d81d_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

CLYBL averts methylmalonyl-CoA mutase inhibition and loss of vitamin B12 by eliminating malyl-CoA

Citrate lyase beta-like protein (CLYBL) is a ubiquitously expressed mammalian enzyme known for its role in the degradation of itaconate, a bactericidal immunometabolite produced in activated macrophages. The association of CLYBL loss-of-function with reduced circulating vitamin B12 levels was proposed to result from inhibition of the B12-dependent enzyme methylmalonyl-CoA mutase (MCM) by itaconyl-CoA. The discrepancy between the highly inducible and locally confined production of itaconate and the broad expression profile of CLYBL across tissues, suggested a role for this enzyme beyond itaconate catabolism. We discovered that CLYBL additionally functions as a metabolite repair enzyme for malyl-CoA, a side-product of promiscuous TCA cycle enzymes. We found that CLYBL knockout cells, accumulating malyl-CoA but not itaconyl-CoA, show decreased levels of adenosylcobalamin and that malyl-CoA is a more potent inhibitor of MCM than itaconyl-CoA. Our work thus suggests that malyl-CoA plays a role in the B12 deficiency observed in individuals with CLYBL loss-of-function. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/614871v2_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1bd0aa2org.highwire.dtl.DTLVardef@54e11org.highwire.dtl.DTLVardef@48661borg.highwire.dtl.DTLVardef@127968f_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Traumatic Brain Injury Exacerbates Alcohol Consumption and Neuroinflammation with Decline in Cognition and Cholinergic Activity

Traumatic brain injury (TBI) is a global health challenge, responsible for 30% of injury-related deaths and significantly contributing to disability. Annually, over 50 million TBIs occur worldwide, with most adult patients at emergency departments showing alcohol in their system. TBI is also a known risk factor for alcohol abuse, yet its interaction with alcohol consumption remains poorly understood. In this study, we demonstrate that the fluid percussion injury (FPI) model of TBI in mice significantly increases alcohol consumption and impairs cognitive function. At cellular levels, FPI markedly reduced the number and activity of striatal cholinergic interneurons (CINs) while increasing microglial cells. Notably, depleting microglial cells provided neuroprotection, mitigating cholinergic loss and enhancing cholinergic activity. These findings suggest that TBI may promote alcohol consumption and impair cognitive abilities through microglia activation and consequently reduced cholinergic function. Our research provides critical insights into the mechanisms linking TBI with increased alcohol use and cognitive deficits, potentially guiding future therapeutic strategies.

neuroscience↗

bioRxiv2024

Liprin-α/RIM complex regulates the dynamic assembly of presynaptic active zones via liquid-liquid phase separation

Presynaptic scaffold proteins, including liprin-, RIM, and ELKS, are pivotal to the assembly of the active zone and regulating the coupling of calcium signals and neurotransmitter release, yet the underlying mechanism remains poorly understood. Here, we determined the crystal structure of the liprin-2/RIM1 complex, revealing a multifaceted intermolecular interaction that drives the liprin-/RIM assembly. Neurodevelopmental disease-associated mutations block the formation of the complex. Disrupting this interaction in neurons impairs synaptic transmission and reduces the readily releasable pool of synaptic vesicles. Super-resolution imaging analysis supports a role for liprin- in recruiting RIM1 to the active zone, presumably by promoting the liquid-liquid phase separation (LLPS) of RIM1. Strikingly, the liprin-/RIM interaction modulates the competitive distribution of ELKS1 and voltage-gated calcium channels (VGCCs) in RIM1 condensates. Disrupting the liprin-/RIM interaction significantly decreased VGCC accumulation in the condensed phase and rendered release more sensitive to the slow calcium buffer EGTA, suggesting an increased physical distance between VGCC and vesicular calcium sensors. Together, our findings provide a plausible mechanism of the liprin-/RIM complex in regulating the coupling of calcium channels and primed synaptic vesicles via LLPS for efficient synaptic transmission and uncover the pathological implication of liprin- mutations in neurodevelopmental disorders.

neuroscience↗

bioRxiv2024

Tracing the genetic diversity of the bread wheat D genome

Bread wheat (Triticum aestivum) became a globally dominant crop after incorporating the D genome from donor species Aegilops tauschii, while evolutionary history shaping the D genome during this process remains elusive. Here, we proposed a renewed evolutionary model linking Ae. tauschii and hexaploid wheat D genome, based on an ancestral haplotype map covering a total of 762 Ae. tauschii and hexaploid wheat accessions. We dissected the evolutionary process of Ae. tauschii lineages and clarified L3 as the most ancient lineage. A few independent intermediate accessions were reported, demonstrating the low-frequent inter-sublineage geneflow enriched the diversity of Ae. tauschii. We discovered that the D genome of hexaploid wheat inherited from a unified ancestral template, but with a mosaic composition that is highly mixed by three Ae. tauschii L2 sublineages located in the Caspian coastal region, suggesting the early agricultural activities facilitate the innovation of D genome compositions that finalized the success of hexaploidization. We further found that the majority (65.6%) of polymorphisms were attributed to novel mutations absent during the spreading of bread wheat, and also identified large Ae. tauschii introgressions from wild Aegilops lineages, expanding the diversity of wheat D genome and introducing beneficial alleles. This work decoded the mystery of the wheat hexaploidization process and the evolutionary significance of the multi-layered origins of the genetic diversity of the bread wheat D genome.

evolutionary biology↗

bioRxiv2024

Ultra-low photodamage three-photon microscopy assisted by neural network for monitoring regenerative myogenesis

Three-photon microscopy (3PM) enables high-resolution three-dimensional (3D) imaging in deeply situated and highly scattering biological specimens, facilitating precise characterization of biological morphology and cellular-level physiology in vivo. However, the use of fluorescent probes with relatively low three-photon absorption cross-sections necessitates high-peak-power lasers for excitation, which poses inherent risks of light-induced damage. Additionally, the low repetition frequency of these lasers prolongs scanning time per pixel, hampering imaging speed and exacerbating the potential for photodamage. Such limitations hinder the application of 3PM in studying vulnerable tissues, including muscle regeneration. To address this critical issue, we developed the Multi-Scale Attention Denoising Network (MSAD-Net), a precise and versatile denoising network suitable for diverse structures and varying noise levels. Our network enables the use of lower excitation power (1/4-1/2 of the common power) and shorter scanning time (1/6-1/4 of the common time) in 3PM while preserving image quality and tissue integrity. It achieves an impressive structural similarity index (SSIM) of up to 0.9932 and an incredibly fast inference time of just 80 milliseconds per frame which ensured both high fidelity and practicality for downstream applications. By utilizing MSAD-Net-assisted imaging, we comprehensively characterize the biological morphology and functionality of muscle regeneration processes through deep in vivo five-channel imaging under extremely low excitation power and short scanning time, while maintaining a high signal-to-background ratio (SBR) and excellent axial spatial resolution. Furthermore, we conducted high axial-resolution dynamic imaging of vascular microcirculation, macrophages, and ghost fibers. Our findings provide a deeper understanding of the mechanisms underlying muscle regeneration at the cellular and tissue levels.

developmental biology↗

bioRxiv2024

RNA splicing variants of the novel long non-coding RNA, CyKILR, possess divergent biological functions in non-small cell lung cancer

The CDKN2A gene, responsible for encoding the tumor suppressors p16(INK4A) and p14(ARF), is frequently inactivated in non-small cell lung cancer (NSCLC). Herein, an uncharacterized long non-coding RNA (lncRNA) (ENSG00000267053) on chromosome 19p13.12 was found to be overexpressed in NSCLC cells with an active, wild-type CDKN2A gene. This lncRNA, named Cyclin-Dependent Kinase Inhibitor 2A-regulated lncRNA (CyKILR), also correlated with an active WT STK11 gene, which encodes the tumor suppressor, Liver kinase B1. CyKILR displayed two splice variants, CyKILRa (exon 3 included) and CyKILRb (exon 3 excluded), which are cooperatively regulated by CDKN2A and STK11 as knockdown of both tumor suppressor genes was required to induce a significant loss of exon 3 inclusion in mature CyKILR RNA. CyKILRa localized to the nucleus, and its downregulation using antisense RNA oligonucleotides enhanced cellular proliferation, migration, clonogenic survival, and tumor incidence. In contrast, CyKILRb localized to the cytoplasm, and its downregulation using siRNA reduced cell proliferation, migration, clonogenic survival, and tumor incidence. Transcriptomics analyses revealed enhancement of apoptotic pathways with concomitant suppression of key cell cycle pathways by CyKILRa demonstrating its tumor-suppressive role. CyKILRb inhibited tumor suppressor microRNAs indicating an oncogenic nature. These findings elucidate the intricate roles of lncRNAs in cell signaling and tumorigenesis.

molecular biology↗

bioRxiv2024

Modeling Mountain Pine Beetle Abundance and Distribution in a Changing Climate

The range of mountain pine beetle (Dendroctonus ponderosae Hopkins) is primarily constrained by climate, with winter temperatures playing a crucial role. Climate change is likely to increase the number of warm days and decrease cold days compared to historical norms, making higher latitudes more suitable habitats. In this work, we explore the potential impacts of environmental covariates on outbreaks of mountain pine beetle under climate change in a selected lodgepole pine area in Alberta. We employ a hierarchical model to examine mountain pine beetle dynamics approaching the end of the century. Our analysis assesses the impact of various climatic covariates and estimates the probability and expected number of infestations across different climate change scenarios. Our results from the hierarchical model underscore the critical role of degree days and overwinter survival probability, displaying an overall trend towards a higher probability and a greater number of outbreaks with increasing temperature. Our results indicate that Alberta is likely to experience widespread infestations in the future.

ecology↗

bioRxiv2024

Robust sub-network fingerprints of brief signals in the MEGfunctional connectome for single-patient classification

Recent studies have shown that the Magnetoen-cephalography (MEG) functional connectome is person-differentiable in a same-day recording with as little as 20 latent components, showing variability across synchrony measures and spectral bands. Here, we succeed with [Formula] components of the functional connectome on a multi-day dataset of 43 subjects and link it to related clinical applications. By optimizing sub-networks of [Formula] regions with 30 seconds of broadband signal, we find robust fingerprinting performance, showing several patterns of region re-occurrence. From a search space of 5.72 trillion, we find 46,071 of many more acceptable solutions, with minimal duplicates found in our optimization. Finally, we show that each of these sub-networks can identify 30 Parkinsons patient sub-networks from 30 healthy subjects with a mean F1 score of 0.716 {+/-} 0.090SD. MEG fingerprints have previously been shown on multiple occasions to hold patterns on the rating scales of progressive neurodegenerative diseases using much coarser features. Furthermore, these sub-networks may similarly be useful for identifying patterns across characteristics for age, genetics, and cognition.

neuroscience↗